A novel nerve transection and repair method in mice: histomorphometric analysis of nerves, blood vessels, and muscles with functional recovery

Lee, Jung Il; Gurjar, Anagha; Talukder, Milton; Rodenhouse, Andrew; Manto, Kristen; OʼBrien, Mary Elizabeth; Govindappa, Prem Kumar; Elfar, John C.

doi:10.1038/s41598-020-78481-1

Cited by 18 publications

(13 citation statements)

References 44 publications

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“…To assess the process of Wallerian degeneration more accurately, we detected the axon and myelin remained in the distal segment of transected sciatic nerve. In this way, the regenerating axons and myelin extending from the proximal nerve into the distal trunk, which occurs in most PNI models, could be avoided [ 36 , 60 ]. From the results of Western blots and immunofluorescence, we found that much more axonal and myelin fragments, as well as their proteins, remain in the cKO group which indicated RhoA conditional knockout in macrophages results in the delayed process of Wallerian degeneration.…”

Section: Discussionmentioning

confidence: 99%

Macrophage-specific RhoA knockout delays Wallerian degeneration after peripheral nerve injury in mice

Wen

et al. 2021

J Neuroinflammation

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Background Plenty of macrophages are recruited to the injured nerve to play key roles in the immunoreaction and engulf the debris of degenerated axons and myelin during Wallerian degeneration, thus creating a conducive microenvironment for nerve regeneration. Recently, drugs targeting the RhoA pathway have been widely used to promote peripheral axonal regeneration. However, the role of RhoA in macrophage during Wallerian degeneration and nerve regeneration after peripheral nerve injury is still unknown. Herein, we come up with the hypothesis that RhoA might influence Wallerian degeneration and nerve regeneration by affecting the migration and phagocytosis of macrophages after peripheral nerve injury. Methods Immunohistochemistry, Western blotting, H&E staining, and electrophysiology were performed to access the Wallerian degeneration and axonal regeneration after sciatic nerve transection and crush injury in the LyzCre+/−; RhoAflox/flox (cKO) mice or Lyz2Cre+/− (Cre) mice, regardless of sex. Macrophages’ migration and phagocytosis were detected in the injured nerves and the cultured macrophages. Moreover, the expression and potential roles of ROCK and MLCK were also evaluated in the cultured macrophages. Results 1. RhoA was specifically knocked out in macrophages of the cKO mice; 2. The segmentation of axons and myelin, the axonal regeneration, and nerve conduction in the injured nerve were significantly impeded while the myoatrophy was more severe in the cKO mice compared with those in Cre mice; 3. RhoA knockout attenuated the migration and phagocytosis of macrophages in vivo and in vitro; 4. ROCK and MLCK were downregulated in the cKO macrophages while inhibition of ROCK and MLCK could weaken the migration and phagocytosis of macrophages. Conclusions Our findings suggest that RhoA depletion in macrophages exerts a detrimental effect on Wallerian degeneration and nerve regeneration, which is most likely due to the impaired migration and phagocytosis of macrophages resulted from disrupted RhoA/ROCK/MLCK pathway. Since previous research has proved RhoA inhibition in neurons was favoring for axonal regeneration, the present study reminds us of that the cellular specificity of RhoA-targeted drugs is needed to be considered in the future application for treating peripheral nerve injury.

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Section: Discussionmentioning

confidence: 99%

Macrophage-specific RhoA knockout delays Wallerian degeneration after peripheral nerve injury in mice

Wen

et al. 2021

J Neuroinflammation

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“…Stretch is another common deformation of nerves, especially for transected nerves undergoing strong retraction due to the elastic endoneurium. [ 37 ] A tensile test was used to pull two nerves connected by adhesives to determine stretching adhesion forces. The DNNA showed a higher failure force and adhesion strength than HA‐Cat, but no significant difference was observed between HA–TU–Cat and DNNA (Figure 3C,D).…”

Section: Resultsmentioning

confidence: 99%

A Dual‐Network Nerve Adhesive with Enhanced Adhesion Strength Promotes Transected Peripheral Nerve Repair

Xue

Shi

Kuss

et al. 2022

Adv Funct Materials

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Peripheral nerve transection has a high prevalence and results in functional loss of affected limbs. The current clinical treatment using suture anastomosis significantly limits nerve recovery due to severe inflammation, secondary damage, and fibrosis. Fibrin glue, a commercial nerve adhesive as an alternative, avoids secondary damage but suffers from poor adhesion strength. To address their limitations, a highly efficacious nerve adhesive based on dual-cross-linking of dopamine-isothiocyanate modified hyaluronic acid and decellularized nerve matrix is reportedr. This dual-network nerve adhesive (DNNA) shows controllable gelation behaviors feasible for surgical applications, robust adhesion strength, and promotes axonal outgrowth in vitro. The in vivo therapeutic efficacy is tested using a ratbased sciatic nerve transection model. The DNNA decreases fibrosis and accelerates axon/myelin debris clearance at 10 days post-surgery, compared to suture and commercial fibrin glue treatments. At 10 weeks post-surgery, the strong adhesion and bioactivity allow DNNA to significantly decrease intraneural inflammation and fibrosis, enhance axon connection and remyelination, aid motor and sensory function recovery, as well as improve muscle contraction, compared to suture and fibrin treatments. Overall, this dual-network hydrogel with robust adhesion provides a rapid and highly efficacious nerve transection treatment to facilitate nerve repair and neuromuscular function recovery.

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“…Tiling and z-stack functions were used to image whole nerve. Maximum intensity projection was used to pull the data from all Z-stacks and represent it as a 2-D image [ 50 , 51 ].…”

Section: Methodsmentioning

confidence: 99%

Erythropoietin-PLGA-PEG as a local treatment to promote functional recovery and neurovascular regeneration after peripheral nerve injury

et al. 2022

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Background Traumatic peripheral nerve injury (TPNI) is a major medical problem with no universally accepted pharmacologic treatment. We hypothesized that encapsulation of pro-angiogenic erythropoietin (EPO) in amphiphilic PLGA-PEG block copolymers could serve as a local controlled-release drug delivery system to enhance neurovascular regeneration after nerve injury. Methods In this study, we synthesized an EPO-PLGA-PEG block copolymer formulation. We characterized its physiochemical and release properties and examined its effects on functional recovery, neural regeneration, and blood vessel formation after sciatic nerve crush injury in mice. Results EPO-PLGA-PEG underwent solution-to-gel transition within the physiologically relevant temperature window and released stable EPO for up to 18 days. EPO-PLGA-PEG significantly enhanced sciatic function index (SFI), grip strength, and withdrawal reflex post-sciatic nerve crush injury. Furthermore, EPO-PLGA-PEG significantly increased blood vessel density, number of junctions, and myelinated nerve fibers after injury. Conclusion This study provides promising preclinical evidence for using EPO-PLGA-PEG as a local controlled-release treatment to enhance functional outcomes and neurovascular regeneration in TPNI.

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A novel nerve transection and repair method in mice: histomorphometric analysis of nerves, blood vessels, and muscles with functional recovery

Cited by 18 publications

References 44 publications

Macrophage-specific RhoA knockout delays Wallerian degeneration after peripheral nerve injury in mice

Macrophage-specific RhoA knockout delays Wallerian degeneration after peripheral nerve injury in mice

A Dual‐Network Nerve Adhesive with Enhanced Adhesion Strength Promotes Transected Peripheral Nerve Repair

Erythropoietin-PLGA-PEG as a local treatment to promote functional recovery and neurovascular regeneration after peripheral nerve injury

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